1. Field of the Invention
The field of the invention is meat processing equipment, and more particularly, equipment for removing natural or artifical casings from sausages.
2. Description of the Background Art
Sausages for human consumption come in a wide variety of compositions. Sausages are, generally speaking, elongated and cylindrical in shape--although they range greatly in size. When sausage is made, its ingredients are stuffed into a casing, which may be a natural casing or an artificial casing made of a synthetic material. The sausage is then cooked in one of many sausage-making processes. The result is generally an elongated, whole sausage or a chain of sausage links.
After producing the sausage, some post-processing may be desired before packaging. Thus, a large bologna may be cut into slices before being packaged as sandwich meat. An artificial casing on wieners may be removed to produce "skinless" wieners. And pepperoni may be skinned and sliced for use in pizza.
Small sausage and linked sausage can be made in natural or artificial casing. When these casings are edible, such sausages are sold and generally consumed with the casing. Larger sausage needs a stronger casing and is generally made in a fiber reinforced plastic casing. This casing adheres to the meat to varying degrees and may even break apart as it is removed from the body of the sausage. This happens particularly with dry sausage where the casing is made brittle by the drying process.
Removal of the fibrous casings may be facilitated by using "easy-to-peel" casings which are impregnated with additives that inhibit the adherence of the casing to the meat. The adherence may be so slight that in some cases, air injected into the casing can inflate it and release it from the meat entirely before the sausage is fed to a casing removal mechanism.
Two ways have been known to feed sausage into sausage processing machines. One is to feed the sausages longitudinally using feed rollers with axes of rotation that are transverse and perpendicular to the longitudinal axis of the sausage. This has been used with "easy-to-peel" casings. The other is to feed the sausage using feed rollers with skewed axes, so that the sausage is fed along a helical path. This has been used for regular casings.
With most casings, there is a hanging string at one end of the sausage. This string can be looped over a cross bar to allow the sausage to hang vertically. This string is also used when the sausage is fed into a sausage peeling machine. There the skin is slit along the full length of the sausage. A pair of peeling rollers are below the sausage feed path, and the hanging string is attracted to the peeling rollers by suction. The skin is then pulled through the rotating peeling rollers and the casing is progressively stripped from the body of the sausage as it is fed past the rollers.
Such a method may be suitable for removing "easy-to-peel" casings, where the casing is inflated by air injection and fully released from the body of the sausage before it is fed into the peeling mechanism. There have been several problems, however, in using such a method to remove casings from sausage. First, "easy-to-peel" casings are more expensive, and therefore, their use is resisted and limited to only a small percentage of the sausage that is produced. Second, slitting the casing for the full length of the sausage usually slits the body of the sausage also and is unacceptable to most producers. Third, air injection alone will not overcome the adherence of regular casings to meat and release them entirely from the sausage. Fourth, gripping the hanging string has not been an adequately reliable way of starting the peeling operation. And fifth, the addition of humidifiers to moisten the casings where they have become dry and brittle, has tended to wet the hanging string and cause it to become wrapped around and stuck to the outside of the casing, where it cannot be suitably attracted to the peeling rollers.
The need remains for better methods and equipment for peeling hard sausages. Such methods and equipment would be of commercial importance in providing sausage products in the form desired by food businesses and consumers.